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The doubly conditioned frequency spectrum does not distinguish between ancient population structure and hybridization
Anders Eriksson1, Andrea Manica2
1Evolutionary Ecology Group, Department of Zoology, University of Cambridge, Cambridge, United KingdomIntegrative Systems Biology Laboratory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia aje44@cam.ac.uk am315@cam.ac.uk.
Molecular Biology and Evolution
|March 15, 2014
Summary
Distinguishing ancient population structure from hybridization is challenging. A spatially structured model can mimic hybridization signals, suggesting the doubly conditioned frequency spectrum (dcfs) has limited power for such distinctions.
Area of Science:
- Population genetics
- Paleogenomics
- Evolutionary biology
Background:
- Differentiating between ancient population structure and hybridization is crucial for understanding gene flow across species boundaries.
- The doubly conditioned frequency spectrum (dcfs) has been proposed as a metric to distinguish these scenarios, notably in studies of Neandertal and modern human admixture.
- Previous analyses suggested that observed dcfs patterns in these hominins could only be explained by hybridization, not just ancient population structure.
Discussion:
- This study demonstrates that a spatially coarse demographic model can lead to misinterpretations of dcfs data.
- A more realistic, spatially structured stepping stone model can generate dcfs patterns consistent with ancient structure alone, without invoking hybridization.
- The findings underscore the significant impact of demographic model assumptions on inferences about hybridization events.
Key Insights:
- The power of the doubly conditioned frequency spectrum (dcfs) to differentiate hybridization from ancient population structure is limited.
- Spatially structured population models can produce dcfs shapes that were previously attributed to hybridization.
- Inferences about recent species hybridization are highly sensitive to the chosen representation of population structure.
Outlook:
- Further research should focus on developing more sophisticated demographic models to accurately disentangle hybridization and population structure.
- Future studies may need to incorporate additional genetic or archaeological data to corroborate findings based on dcfs.
- Refined analytical approaches are needed to robustly assess gene flow and admixture in ancient populations.
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